Add Text_Diff via pyrus.

vendor/pyrus/.pear2registry

vendor/pyrus/docs/Text_Diff/Text/docs/examples/1.txt

vendor/pyrus/docs/Text_Diff/Text/docs/examples/2.txt

vendor/pyrus/docs/Text_Diff/Text/docs/examples/diff.php

vendor/pyrus/php/Text/Diff.php

vendor/pyrus/php/Text/Diff/Engine/native.php

vendor/pyrus/php/Text/Diff/Engine/shell.php

vendor/pyrus/php/Text/Diff/Engine/string.php

vendor/pyrus/php/Text/Diff/Engine/xdiff.php

vendor/pyrus/php/Text/Diff/Mapped.php

vendor/pyrus/php/Text/Diff/Renderer.php

vendor/pyrus/php/Text/Diff/Renderer/context.php

vendor/pyrus/php/Text/Diff/Renderer/inline.php

vendor/pyrus/php/Text/Diff/Renderer/unified.php

vendor/pyrus/php/Text/Diff/ThreeWay.php

vendor/pyrus/php/Text/Diff3.php

vendor/pyrus/tests/Text_Diff/Text/tests/1.txt

vendor/pyrus/tests/Text_Diff/Text/tests/2.txt

vendor/pyrus/tests/Text_Diff/Text/tests/3.txt

vendor/pyrus/tests/Text_Diff/Text/tests/4.txt